1. Field of the Invention
The present invention relates to a method for radar measurement, in particular for interferometric radar measurement by transmitting and receiving radar signals with at least two spatially separated radar systems, where a signal exchange between the two radar systems takes place to determine parameters relevant to the measurement.
2. Discussion of Background Information
Such a method is known, e.g., from EP 1 065 518. This describes a high-resolution synthetic aperture radar system (SAR system) which includes a number n of SAR systems on carrier platforms carried by satellites or aircraft. It is provided in particular here that the internal oscillators of the SAR systems that are used as a time reference, are synchronized among themselves in that the oscillator frequency of a main oscillator is transmitted via a microwave connection or a laser connection to the other oscillators.
Eineder, M.: Oscillator Clock Drift Compensation in Bistatic Interferometric SAR. IGARSS 2003, Toulouse, IEEE, Proceedings of IGARSS'03, (2003) describes the compensation of the drift of time references with SAR systems in which the transmitter of the radar signals is arranged spatially separate from the receivers of the radar signals on different satellites (cartwheel arrangement). Here too the frequency of the internal oscillators is exchanged via an inter-satellite connection between the receiver satellites in order to achieve a synchronization of the internal time references.
However, these methods according to the prior art require separate inter-satellite connections via which a transmission of the oscillator frequency must take place. Further measurement-relevant parameters cannot be determined with these methods.
In contrast, U.S. Pat. No. 6,552,678 provides a method for interferometric SAR radar measurement with the aid of two satellites which, according to the text of U.S. Pat. No. 6,552,678, manages without any synchronization at all of the radar signals of the two satellites.